The present invention is related to commonly assigned co-pending Provisional patent applications entitled xe2x80x9cSYSTEMS AND METHODS FOR ELECTROSURGICAL TISSUE AND FLUID COAGULATIONxe2x80x9d and xe2x80x9cSYSTEMS AND METHODS FOR ELECTROSURGICAL TISSUE RESECTION AND ABLATIONxe2x80x9d, filed on Oct. 23, 1997, non-provisional patent application Ser. No. Unassigned, filed on Oct. 2, 1997, entitled xe2x80x9cSYSTEMS AND METHODS FOR ELECTROSURGICAL TISSUE CONTRACTIONxe2x80x9d U.S. application Ser. No. 08/753,227, filed on Nov. 22, 1996, U.S. application Ser. No. 08/687,792, filed on Jul. 18, 1996, and PCT International Application, U.S. National Phase Serial No. PCT/US94/05168, filed on May 10, 1994, which was a continuation-in-part of application Ser. No. 08/059,681, filed on May 10, 1993, which was a continuation-in-part of application Ser. No. 07/958,977, filed on Oct. 9, 1992, which was a continuation-in-part of application Ser. No. 07/817,575, filed on Jan. 7, 1992, the complete disclosures of which are incorporated herein by reference for all purposes. The present invention is also related to commonly assigned U.S. Pat. No. 5,683,366, filed Nov. 22, 1995 and patent application Ser. No. 08/485,219, filed on Jun. 7, 1995, the complete disclosures of which are incorporated herein by reference for all purposes.
The present invention relates generally to the field of electrosurgery, and more particularly to surgical devices and methods which employ high frequency electrical energy to treat a patient""s skin, including skin resurfacing procedures, the removal of pigmentations, vascular lesions, scars and tattoos, hair removal and/or transplant procedures, treatment of skin cancer, skin rejuvenation (e.g., wrinkle removal) and the like.
In early dermatology procedures, cosmetic surgeons often employed chemical peels and/or dermabrasion techniques to remove outer layers of the patient""s skin to rejuvenate wrinkled skin or to remove skins disorders, such as acne, lesions, early skin cancer, etc. These dermabrasion and chemical procedures, however, are difficult to control, requiring great surgical skill. In addition, these somewhat inelegant techniques often cause excessive bleeding, collateral tissue damage and patient discomfort.
In an effort to overcome some of the limitations of dermabrasion and chemical peels, lasers have been developed for use in cosmetic surgery. Lasers have improved the accuracy of skin resurfacing procedures, and they have reduced collateral damage to the tissue surrounding and underlying the treatment site. In laser dermatology applications, a handpiece is typically used to guide the output of a laser to the patient""s skin, and to form a laser spot of a desired size on the region of the skin which is to be treated. The handpiece is typically attached to one end of an articulated arm which transmits the output of a medical laser (such as CO2 or Er: YAG lasers) to the handpiece and allows the handpiece a wide range of motion.
Although initially promising, lasers suffer from a number of drawbacks in dermatology procedures. In the first place, laser equipment can be very expensive because of the costs associated with the laser light sources. Moreover, those lasers which permit acceptable depths of necrosis (such as excimer lasers, erbium:YAG lasers, and the like) provide a very low volumetric ablation rate, requiring numerous passes over the same treatment area which amounts to longer procedural times. In addition, erbium:YAG lasers generally do not provide effective hemostasis during the procedure, resulting in excessive bleeding which disrupts the surgeon""s view of the treatment site. The CO2 lasers provide a higher rate of ablation and an increased depth of tissue necrosis than their erbium: YAG counterparts. On the other hand, CO2 lasers often create significant residual thermal injury to tissue at and surrounding the treatment site, which requires long healing periods for the patient. In addition, CO2 lasers are associated with much pain and, therefore, require a lot of anesthesia, which increases the cost and length of the procedure.
In the treatment of vascular lesions, lasers are used to irradiate the surface of the skin. The laser energy penetrates through the skin and is absorbed in the blood, which coagulates and collapses the vein. Unfortunately, there are also problems associated with the use of lasers in these procedures. For example, although most of the laser energy passes through the tissue to the vessel, scattering and absorption of the light take place in the tissue. This absorption can cause significant changes in skin coloration and even scarring.
Monopolar electrosurgical instruments have been used to effect electro-dessication of abnormalities, such as lesions, skin tags, viral warts, pigment nevi, moles and skin cancer. For example, Conmed Corporation manufacturers a monopolar device, termed the Hyfrecator(trademark) having a single active electrode at the tip of an electrosurgical probe. In these procedures, the skin abnormality is typically removed with a scalpel, and a low voltage is applied to the active electrode in contact with the target tissue to deliver electric current through the tissue and the patient to a dispersive pad or indifferent electrode. The voltage desiccates the remaining abnormal tissue, and coagulates severed blood vessels at the target site. The remaining tissue is then removed with a sponge or similar material. The voltage generally must be low enough to prevent charring and potential scarring of the underlying dermis.
The present invention provides systems, apparatus and methods for selectively applying electrical energy to structures on the external surface of a patient""s body. The systems and methods of the present invention are useful in dermatological procedures, i.e., surface treatment of the patient""s outer skin, such as the epidermis and/or the underlying dermis. For example, the present invention is particularly useful for surface tissue ablation on the epidermis and/or collagen shrinkage in the epidermis or dermis, e.g., the removal of pigmentations, vascular lesions (e.g., leg veins), scars, tattoos, etc., and for other surgical procedures on the skin, such as tissue rejuvenation, cosmetic surgery, wrinkle removal, hair removal and/or transplant procedures.
In one aspect of the invention, a method includes positioning one or more electrode terminal(s) on the distal tip of an instrument in close proximity to a target site on an external body surface of the patient. High frequency voltage is applied to the electrode terminal(s) to elevate the temperature of collagen fibers within the tissue at the target site from body temperature (about 37xc2x0 C.) to a tissue temperature in the range of about 45xc2x0 C. to 90xc2x0 C., usually about 60xc2x0 C. to 70xc2x0 C., to substantially irreversibly contract these collagen fibers. In a preferred embodiment, an electrically conducting fluid is provided between the electrode terminal(s) and one or more return electrode(s) positioned proximal to the electrode terminal(s) to provide a current flow path from the electrode terminal(s) away from the tissue to the return electrode (s).
The current flow path may be generated by directing an electrically conducting fluid along a fluid path past the return electrode and to the target site, or by locating a viscous electrically conducting fluid, such as a gel, at the target site, and submersing the electrode terminal(s) and the return electrode(s) within the conductive gel. The collagen fibers may be heated either by passing the electric current through the tissue to a selected depth before the current returns to the return electrode(s) and/or by heating the electrically conducting fluid and generating a jet or plume of heated fluid, which is directed towards the target tissue. In the latter embodiment, the electric current may not pass into the tissue at all. In both embodiments, the heated fluid and/or the electric current elevates the temperature of the collagen sufficiently to cause hydrothermal shrinkage of the collagen fibers.
In a specific configuration, the electrode terminal(s) are brought into contact with, or close proximity to, the target tissue so that the electric current passes directly into the tissue to a selected depth. In this embodiment, the return electrode(s) draw the electric current away from the tissue site to limit its depth of penetration into the tissue.
In another aspect of the invention, a high frequency voltage is applied to one or more electrode terminal(s), and a layer of the epidermis is removed from the patient. In some embodiments, the high frequency voltage applied to the electrode terminal(s) creates sufficient heat within the skin to decouple or physically separate the epidermis layer from the underlying papillary dermis. The epidermis layer may then be removed by flushing the treatment site with a fluid, or brushing the epidermis layer away from the treatment site, e.g., with a gauze cloth. In this embodiment, the energy applied to the tissue may be further selected to contract the collagen tissue within the underlying dermis as the epidermis layer is being decoupled or separated therefrom. This method removes the surface layer of the skin, while tightening the underlying dermis to remove wrinkles and rejuvenate the skin.
In other embodiments, the epidermis layer is removed by molecular dissociation or disintegration processes. In these embodiments, the high frequency voltage applied to the electrode terminal(s) is sufficient to vaporize an electrically conductive fluid (e.g., gel or saline) between the electrode terminal(s) and the tissue. Within the vaporized fluid, a ionized plasma is formed and charged particles (e.g., electrons) are accelerated towards the tissue to cause the molecular breakdown or disintegration of several cell layers of the tissue. This molecular dissociation is accompanied by the volumetric removal of the tissue. The short range of the accelerated charged particles within the plasma layer confines the molecular dissociation process to the surface layer to minimize damage and necrosis to the underlying tissue. This process can be precisely controlled to effect the volumetric removal of tissue as thin as 10 to 50 microns with minimal heating of, or damage to, surrounding or underlying tissue structures. A more complete description of this phenomena is described in commonly assigned U.S. Pat. No. 5,683,366, the complete disclosure of which is incorporated herein by reference.
During the surgical procedure, the electrode terminal(s) will preferably be spaced away from the target tissue by a small distance, e.g., about 0.05 to 5 mm. This spacing allows for the continual resupply of electrically conducting fluid at the interface between the electrode terminal(s) and the target tissue surface. This continual resupply of the electrically conducting fluid helps to ensure that the thin vapor layer or region will remain over at least a portion of the electrode terminal(s) between the electrode terminal(s) and the tissue surface. Preferably, the electrode terminal(s) will be translated and/or rotated transversely relative to the tissue, i.e., in a light brushing motion, to maintain the supply of electrically conducting fluid in the region between the electrode terminal(s) and the tissue. This dynamic movement of the electrode terminal(s) over the tissue site also allows the electrically conducting fluid to cool the tissue surrounding recently removed areas to minimize damage to this surrounding tissue.
In another aspect of the invention, a method of treating an elongated blood vessel in tissue under the surface of the skin is provided. In this method, one or more electrode terminals are positioned in close proximity to the blood vessel, and a sufficient high frequency voltage is applied to the electrode terminal(s) to coagulate blood within the vessel, causing the vessel to collapse. The electrode terminal(s) may be positioned on the external surface of the skin, or they may be introduced through a percutaneous penetration in the outer skin surface to the blood vessel. In the latter embodiment, the percutaneous penetration may be generated with the electrode terminal(s) by applying sufficient energy to the electrode terminal(s) to remove or ablate a portion of the outer skin surface. The electrode terminal(s) are then moved axially through the skin to generate a hole or channel to the blood vessel.
Apparatus according to the present invention generally include an electrosurgical probe or handpiece having a shaft or handle with proximal and distal ends and one or more electrode terminal(s) at the distal end. The apparatus will preferably further include a fluid delivery element for delivering electrically conducting fluid to the electrode terminal(s) and the target site. The fluid delivery element may be located on the probe, e.g., a fluid lumen or tube, or it may be part of a separate instrument. Alternatively, an electrically conducting gel or spray, such as a saline electrolyte or other conductive gel, may be applied the target site. In this embodiment, the apparatus may not have a fluid delivery element. In both embodiments, the electrically conducting fluid will preferably generate a current flow path from the electrode terminals to one or more return electrode(s). In an exemplary embodiment, the return electrode is located on the probe and spaced a sufficient distance from the electrode terminal(s) to substantially avoid or minimize current shorting therebetween and to shield the return electrode from tissue at the target site.
In a specific configuration, the electrosurgical probe will include an electrically insulating electrode support member having a tissue treatment surface at the distal end of the probe. One or more electrode terminals are coupled to, or integral with, the electrode support member. In one embodiment, an electrode array including a plurality of isolated electrode terminals are embedded into the electrode support member such that the electrode terminals are substantially flush with the tissue treatment surface of the electrode support. For superficial removal of a few layers of skin cells, for example, the electrode terminals preferably extend or recede from the support by less than 0.15 mm to limit the ablation rate of underlying cells, thereby allowing the precise removal of thin layers of tissue. In an exemplary embodiment, the electrode terminal(s) have a substantially elongate shape, usually having a width of about 0.01 mm to 2 mm, preferably about 0.1 to 0.5 mm and a length of about 0.5 to 30 mm, preferably about 3 to 7 mm. In this embodiment, the probe is usually traversed along the skin in a direction that is substantially perpendicular to the longitudinal axis of the electrode terminal(s). Applicant has found that this increases the uniformity of treatment on the surface of the skin.
In another aspect of the invention, the electrode support member comprises a plurality of wafer layers bonded together, e.g., by a glass adhesive or the like. The wafer layers each have conductive strips plated or printed thereon to form the electrode terminal(s) and the return electrode(s). In one embodiment, the proximal end of the wafer layers will have a number of holes extending from the conductor strips to an exposed surface of the wafer layers for connection to electrical conductor lead traces in the electrosurgical probe or handpiece. The wafer layers preferably comprise a ceramic material , such as alumina, and the electrode will preferably comprise a metallic material, such as gold, platinum, tungsten, palladium, silver or the like.
In a specific configuration, the electrode support comprises a multilayer ceramic wafer having at least two strips of gold plated on its distal surface and one or more strips of gold plated onto its lateral surfaces. The gold on the distal surface functions as the active electrode terminals, and the gold plated on the lateral surfaces functions as the return electrodes. The active electrode terminals are electrically isolated from each other, and coupled to a lead wire by a gold plated via or hole in the ceramic wafer. The electrode support may have additional electrode terminals plated thereon that function as additional active or return electrodes. In one embodiment, the electrode support includes a pair of outer electrode terminals having a substantially larger surface area than the inner electrode terminals. In this embodiment, the larger, outer electrode terminals serve to heat the tissue so as to provide coagulation of severed blood vessels, or to induce the contraction of collagen fibers in underlying tissue layers, e.g., the dermis, and the inner, small electrode terminals function to remove tissue through molecular dissociation processes.
In another aspect of the invention, an electrosurgical probe comprises a reusable (i.e., sterilizable) handle removably coupled to a disposable tip having an electrode support and one or more electrode terminal(s) thereon. The handle includes a connector for coupling to a high frequency voltage supply and the disposable tip includes an electrical coupling for removably coupling the electrode terminal(s) to the connector. In the preferred embodiment, the probe will further include a fluid delivery element, such as a fluid lumen or tube, having an opening near the electrode terminal(s) for delivering electrically conducting fluid to the electrode terminal(s).
The system may optionally include a temperature controller coupled to one or more temperature sensors at or near the distal end of the probe. The controller adjusts the output voltage of the power supply in response to a temperature set point and the measured temperature value. The temperature sensor may be, for example, a thermocouple, located in the insulating support that measures a temperature at the distal end of the probe. In this embodiment, the temperature set point will preferably be one that corresponds to a tissue temperature that results in the contraction of the collagen tissue, i.e., about 60xc2x0 C. to 70xc2x0 C. Alternatively, the temperature sensor may directly measure the tissue temperature (e.g., infrared sensor). This embodiment is advantageous in situations when the surgeon is moving the probe transversely across the tissue.
A further understanding of the nature and advantages of the invention will become apparent by reference to the remaining portions of the specification and drawings.